56 On Chemical Philosophy. 
of Lavoisier, and the discovery of the gases, to consider aud speak 
of the solution of substances in this power, as that which formed 
the gaseous state of existence. Indeed, in proof of this, we 
find them with great difficulty refraining from doing so, affording 
a remarkable instance how, even in the strongest minds, nature 
and truth will struggle with prejudice and error. ‘* It is pro- 
bable,” says Lavoisier *, * that the separation of the particles of 
bodies, occasioned by caloric, depends, in a similar manner, en 
acertain combination of attractive powers, which, in conformily 
with the imperfection of our knowledge, we endeavour to express 
by saying that caloric communicates a power of repulsion to the 
particles of bodies.” In another place he says: “ It is extremely 
difficult te form an accurate notion of this repulsion acting upon 
very minute particles, placed at great distances from each other.” 
In my opinion, it is utterly impossible. Perhaps the common and 
modern notions of attraction and repulsion, either prevented him 
from seeing as much distinctly, or deterred him from expressing 
it; but he is often obliged to come very near the truth in such 
passages as these: “ In each species of gas, I shall,” says he, 
*€ distinguish between the caloric which in some measure an- 
swers the purpose of a solvent, and the substance which is in 
combination with caloric, and forms the base of the gas.” Why 
say “ im some measure,” and not at once in plain terms 7 is 
the solvent ? Indeed almost all the chemists of that period, not- 
withstanding this attachment to former views, generally speak 
of the solution of bodies in caloric: in fact, so simple and eb- 
vious is the idea, and so evidently must it have obtruded itself on 
their minds, that it is wonderful they could adopt any other 
mode of expression. What other reasons had thev for adopt- 
ing the word caloric ? or how otherwise could the Lavoisierian 
theory of combustion be intelligible? Chaptal and Foureroy 
‘speak of the solution of substances in fire and water as simi- 
lar. Fourcroy says, ‘* Calorie sometimes adheres so forcibly to 
bodies, that it prevents their combining with gthers. Thus 
many are dissolved into gas or other elastic fluids, as steam ; 
some will neither unite with other bodies, nor with one another, 
so jong as they retain this state of invisible solution in caloric 
so that recourse must be had to double elective attractions, to 
effect their combinations.”? And again: ‘* The attractionof ca-- 
loric for some bodies is so great, that it is frequently employed 
with advantage for separating these substances from the com- 
pounds into whieh they enter, and for analysing and decompos- 
ing compound bodies. This is what we do in distillation, and 
in all the decompositions effected by fire alone, or calori¢ aps 
* See page 25, Elements. 
plied 
